In wireless communications, when the intensity of an input signal is low, an amplifier (e.g. a low noise amplifier a.k.a. LNA) can be used to amplify the input signal. When the intensity of the input signal is high enough, the control circuit can be switched to a bypass mode to bypass the amplifier so as to reduce power consumption.
To perform the abovementioned operation, a bypass circuit may be coupled between an input terminal and an output terminal of the amplifier, and a switch can be installed at the output terminal of the amplifier. When the intensity of the input signal is high enough, the switch can be turned off so as to output the input signal via the bypass circuit. However, when the intensity of the input signal is high enough, unexpected conduction may happen on semiconductor junctions of transistors of the amplifier, and linearity of the bypass circuit may be affected.